[PATCH 3.2 53/77] dm btree: fix bufio buffer leaks in dm_btree_del() error path

Ben Hutchings
2015-12-24T15:43:36Z

From: Joe Thornber <ejt@redhat.com>

commit ed8b45a3679eb49069b094c0711b30833f27c734 upstream.

If dm_btree_del()'s call to push_frame() fails, e.g. due to
btree_node_validator finding invalid metadata, the dm_btree_del() error
path must unlock all frames (which have active dm-bufio buffers) that
were pushed onto the del_stack.

Otherwise, dm_bufio_client_destroy() will BUG_ON() because dm-bufio
buffers have leaked, e.g.:
device-mapper: bufio: leaked buffer 3, hold count 1, list 0

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/md/persistent-data/dm-btree.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -231,6 +231,16 @@ static void pop_frame(struct del_stack *
dm_tm_unlock(s->tm, f->b);
}

+static void unlock_all_frames(struct del_stack *s)
+{
+ struct frame *f;
+
+ while (unprocessed_frames(s)) {
+ f = s->spine + s->top--;
+ dm_tm_unlock(s->tm, f->b);
+ }
+}
+
int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
{
int r;
@@ -286,9 +296,13 @@ int dm_btree_del(struct dm_btree_info *i
f->current_child = f->nr_children;
}
}
-
out:
+ if (r) {
+ /* cleanup all frames of del_stack */
+ unlock_all_frames(s);
+ }
kfree(s);
+
return r;
}
EXPORT_SYMBOL_GPL(dm_btree_del);